I received the RE0 sample from Fang @ Head-Direct today and I thought I'll share some pictures with all of you first before I finish the 50hrs burn-in. Review will come after that, probably by late Sunday or early Monday. Cheer.

The IEM, various eartips, and the replacement filters

Metal housing

Side by side with the RE1

Y-splitter section

Mini jack. RE1 on the left, RE0 on the right.

*In case you are wondering, here is my early impression: It is all good

[UPDATE]

Package & Build Quality
I got the RE0 in a sampling package, so there isn't much of anything to say about the packaging. However, all the accessories are included in the package, which are three set of single flange eartips (various sizes), a set of normal bi-flanges, and a set of Head-Direct's very own 'big' bi-flanges. Five pair of replacement filters are also included, which is a great plus since these are what missing from the original RE1 /RE2 re lease. I guess Head-Direct is paying more attention to finer detail of their products since the first launch of their own IEM line.

The IEM earpieces are made out of some kind of metal, which I guess could be aluminum. The body seems to be mostly anodized too. The earpieces housing resembles a few others Chinese IEM design, but it is not surprised since Head-Direct had adapted (more or less) generic design on their RE1 / RE2 before. It won't win any beauty award, but housing design usually isn't among the top priority of small IEM companies anyway. As far as I can tell, the earpiece is solidly built and that’s good enough for me.

The cable on RE0 is slightly different from those on RE1 / RE2. I like those RE1 / RE2 cable as they are more resistance to wear and tear, but they do have some residual memory effect - meaning they will retain the rough shape of where they are stored in (a problem shared by TF10 as well). If you are like me, which don't use one IEM daily, you will find your RE1 / RE2's cable retaining a little bit of the storage shape and have to put them outside for a while so the memory effect will go away. In rough examination, RE0 seems to have the same kind of cable, but it is not totally identical. RE0's cable is actually less spongy and not as bendable, thus it doesn't tend to memorize its shape as easy as the RE1 / RE2 cable, but you will probably be better off not taking the chance on storing it in very tight, confined place. On the other hand, RE0 cable is just as durable as the RE1 / RE2 cable. The overall cable length is about 1.3m, which is just about perfect and no extension cable is needed this time. The mini jack is also more solid than the original, very light built RE1 / RE2 jack, though I have found no problem on either of them.

Isolation and Fit
Isolation is better on the RE0 than Head-Direct’s previous models. Even with a single flange, I can achieve the same degree of isolation as with RE1 on big bi-flanges. This is partially thanks to the fact the RE0 is a closed design (what seems to be small vent holes on the back have no sonic impact on the SQ), as compare to RE1 / RE2 semi-opened design. I estimated the isolation to be around -23~26dB, which is on par with most of the IEM these days.

I used the stock mid-size single flange for my audition and not the (personally usually preferred) big bi-flanges because I don’t find them to be of much different. I get comfortable seal with both. In comparison with the previous Head-Direct’s models, RE) seems to be easier to wear, probably due to the smaller earpieces. The cable is about as microphonics as most IEM wearing in earbud / regular style. On side note, you can use Comply T400 / T500 on RE0, though I didn’t use them (as I don’t feel like I need them).

Sound Quality
My main reviewing rig consists of: Dell XPS420 – Foobar2K - ASIO – 3MOVE. The music of choice is my regular reviewing CD (see this/) and a few ripped albums on my computer. The IEM of choice for A/B’ing is TF10 and SE530. RE0 has been burnt in for roughly 50hrs before the review and I don’t find any significant change in SQ during the whole process.

Both TF10 and RE0 have pretty good detail and treble extension but RE0 is able to present everything without a sense of sibilance (even TF10 can have a small bit of harshness on the brass sometime). In comparison, the fine detail, like the crispiness of the brass, is usually lost in SE530. What RE0 truly out shines TF10 and SE530 is on the highest note: For the first time, I am able to hear the finest of the finest detail on strings instruments without using a pair of Etymotic. To my surprise, RE0 even has more upper treble than my amped iM716 in HD mode.

RE0’s mid are a bit recessed in comparison. Its vocal is more laid back and further away, but the nice thing is it doesn’t sound too distance from the rest of the spectrum, which actually gives it a sense of smoothness. In comparison, TF10’s mid sounds more up-front while SE530 mid is more aggressive (which is a bit too much on upper vocal and tend to make all the “ssss…” is a bit too sharp).

In the bass department, TF10 has the most mid-bass (with a very slight sense of boom) and SE530 has the best body and control (speed wise). RE0’s bass extends quite far down and capable of matching that of SE530 or TF10. Though far from bass light, what RE0’s bass lacks is a good body, Bass often comes and goes too quickly to give the sense of fullness. On the plus side, RE0 does have enough impact on its bass. Overall, RE0’s bass is good, but it is only better than average IEM and yet to be able to match performance of real bass monsters like the Atrio series.

Since RE0 has a closed design, it will never be able to match wide soundstage of Head-Direct’s previous models (especially the amped RE1). However, it really isn’t bad at all. I find RE0 to be on par with SE530 soundstage wise, which is quite average on top-end IEM. Do note that RE0 is quire revealing, low bitrates garbage will not likely to pass unnoticed.

Efficiency
So how well RE0 is able to run unamped? Here is an example: to match the loudness of RE0 with TF10 and SE530 on my iriver clix2, I have to set it at 20~22/40, where TF10 is 10~12/40 and SE530 is 8~10/40. Basically, RE0 is neither very efficient nor very inefficient. You can probably run it unamped with an iPod by setting the volume to vary loud, but an amp would probably do a better job. I do find small amp like FiiO E3(which I believe comes with the IEM when purchased) and E5 are enough to give a satisfying result (and the bass boost will give RE0 a better bass). Of course, a better amp is always…better.

Conclusion
RE0 is by far the best dynamic IEM I even heard, but it is not just good as a dynamic– it is actually some of the best sounding IEM there are, with enough detail to put many balanced armature IEM to shame. RE0 is a pair of ultra detail IEM with a slightly lay back mid and a good bass. The overall sound signature is balanced, with a much fainted sense of warmness due to the rather smooth frequency response curve. By SQ alone, it is really a big toss b/w RE0, TF10, and SE530 to say exactly which one is the better of the batch - I like TF10 for its airiness and soundstage, SE530 for its mid presentation, and RE0 for its fine treble detail and overall smoothness. I’ll probably pick soundstage (because of my own taste) over other factors in the end if I am only allowed to keep one, but I have seen another contender for the best IEM nonetheless. RE0 will be retailed for $199 – not really a cheap price but it is still cheaper than those in the same class of SQ and should worth some serious consideration.

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The following is a ranking system I used on my previous multiple IEM review and comparison thread . I adapted the same system here so that those of you who are familiar with that thread with be able to get a general sense of what rating this IEM will fit in, and perhaps it will also serve well as a quick sum up. Note: A new, more detail ranking system is currently under revision and will be used on my future multiple IEM review thread. The old ranking system will be used during the transition period. [UPDATE] You will find a more advanced ranking on my new Multiple IEM shootout v.2 thread.
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Variation: n/a.Transducer: 9mm Single DynamicSpec: 64Ω (@1kHz) | 100dB SPL | 15Hz ~ 22KHzCord Style: Y-cord, 1.30m.Mini Jack Style: Gold plated straight style, light build.Eartips Used: Single flangesPackaging: n/a (sampling package)Build Quality: ★★★★ (solid but nothing spectacular)Accessories: ★★★★ (multiple replacement filter set included)Isolation: ★★★☆ (Around -23~26dB, decent isolation enough for daily use)Microphonics: ★★★ (earbud style)Comfort: ★★★★★Soundstage: ★★★★ (not as open and airy as the RE1 due to its closed design)Sound Quality: ★★★★☆ (Balanced, with a much fainted sense of warmness due to the rather smooth frequency response curve. Ultra fine detail like that of Etymotic, slightly lay back mid with a good bass. Capable of rivaling some of the best universal IEM in the market)Value: ★★★★☆ (Reasonably priced for its great SQ, but still not yet the best value because of minor issues - see remark*)Remark: RE0 is an excellent IEM that addressed some of the short coming of RE1 – amp is more or less not as important, detail has been significantly improved, and so is the overall SQ. All in all, it is the best of the family – and it put the IEM a few steps closer to being the best IEM in the market. *With multiple new top-end IEM just being released into the market and a few high-end IEM getting major discount because of the poor economy and holiday session, it is tough to convince people to pay their money. The reasons why RE0 doesn’t receive the top value rating are 1) because user would probably be getting an amp down the road and 2) there are a few sub-$200 deals that come with very nice packaging with a lot of accessories even though they might not be as good in SQ.

[UPDATE AGAIN]
Here is a mod you can try on your RE0 - it is the same mod as the RE1 mod I described before. Basically, you remove the foam inside the nozzle (behind the mesh-like filter) to improve the SQ.

SQ wise, you will find that the mid range is no longer recessed. It has moved forward and became quite lively. The soundstage is also improved, capable of matching (and even a little surpassing) TF10. There is even more detail than before, but comes with a downside - you will detect a very slight hint of sibilance on bright music on higher volume now, but nothing terrible.

I have said it before that I would rank RE0 below TF10 and SE530 on SQ, but with the mod I'll probably rank it higher than SE530 and place it very close or even on par with TF10.

First, it is not an carbon copy of Vibe. Second, design of the earpiece housing in China is commonly shared / copied / revised among many manufacturers. For example, OVC T50 and SoundMAGIC PL-18S are all sharing very similar design as RE0 (and if I am not mistaken, OVC is/was the OEM of V-moda).If there is one common trend about Chinese headphone manufacturers, it will be the fact that they value function over form most of the time and will adapt common design in the market to lower cost.

BTW, though I have never tried Vibe before nor know how it fits, I do know the fit on RE0 is pretty good.

Impedance is indeed lower in the RE0, but not that much lower (plus the sensitivity isn't very high). Basically it means you need to turn the volume up but you can probably use it unamped on an iPod (which I don't own thus can't be sure of). I did try it with small amps like Travagan's Colors, FiiO E3 and E5 with satisfying result.